car loses power under load

[knight007]

ok i searched and couldnt find anything that fit with my problem. ok so here it is i start up the car it runs real rough at idle and will stumble then die usually if i dont give it gasto start. Then when i start to drive down the road at 3 grand itll feel like it hits a flat spot in the power band or something but as soon as i hit 4 grand all the power comes back. it does this in every gear. The thing is it wont do it all the time. it does it every time i do it but when it warms up more it wont do it as much. ive checked and changed the spark plugs (ngk iridiums) checked the coil pack (msd and stock one) checked the injectors. im running out of ideas im thinking now more towards maybe a vacumn leak or something any help or ideas would be appreciated i just wanna drive my car again and it act semi right. thanks

 

[BigRand]

how exactly did you check the coil pack?

Also does your car sound like a subaru at idle and below 4grand?

 

[knight007]

yea after i wrote that about the coil pack i thoguht someone might ask i had the msd on there and thought ok it just died on me or something so i went back to my stock one and it still did so my buddy got a brand new one from his work and it still did it.

as for the suburua sound it does that at idle but it only feels like a flat spot at 3 grand everything before that and after 4 is normal except for the idle and it just idles and almost dies when i first start it up after that it doesnt do it.

 

[dirtysouthpinoy]

My car use to do that, it was really bad when i had the air conditioning on. But after i changed the spark plug wires it was all good. try doing that

 

[cimotorsports]

If you can, do a compression test and make sure you have same numbers across the board, if that checks out then next thing i would do is check the plug condition and probably replace those out anyways, make sure you have the proper heat range plug also, ive noticed that anything other then a standard ngk copper plug likes to crap out really fast on our cars.. if that all checks out goo move onto actually checking the wiring going into the coil and doing a ohm test on the coil output terminal, even inspect the bottom of the actual coil for cracking, seen some do that and arc off the valve cover and you would never even see it

 

[BigRand]

+one, also be prepared to replace the wires as well.

 

[knight007]

the plugs and the plug wires are good and yea i checked the coil pack and it was fine.

As for the compression numbers there all 250 across the board which i know is high but i used two different compression testers and took it up to the mitsu dealer here and they said the same.

The only thing i havent done is check the ohm's to the coil pack.

 

[knight007]

could it be my fuel filter?

 

[dr1665]

the plugs and the plug wires are good

How do you know this?

You are describing, to perfection, the symptoms of bad plug wires. Lose the Iridium nonsense and get a set of properly gapped NGKs. Then either swap your plug wires with another car not experiencing the problem or replace them with a new set from Autozone.

If you're really bored and want to play cars some more, try doing a power balance test. While the car is idling funky, disconnect one plug wire at a time. You should see a difference in how the car runs. Yank #1 and note how the engine runs. Then reconnect and yank #2. Do this for all the wires. Should you remove a plug wire and it's like nothing happened, then that is likely the cylinder with the trouble.

Shut the car off, swap that wire with the other one of the same length, and try it again. If the idle problem moves with the wire, then you have even further proof that the wire is the culprit. 99% of the time, when someone comes to the boards with this stutter, misfire, flat spot around 3000rpm, it's just bad plug wires. $30 for a set of Bosch from Autozone with the lifetime warranty is all you'll ever need until you get to the point of requiring an ignition amp.

You're wasting your money on Iridium anything and you don't want platinum either.

 

[knight007]

Ill try the spark plug thing. yea those spark plugs are gone im gonna put some regular ngk's in there. The reason why those are in there is because i got them for free. Thanks for the help though i wont be able to get home for another 2 weeks but when i start messin with it again ill let yall know. thanks again for all the help

 

[VelocitàPaola]

If you're really bored and want to play cars some more, try doing a power balance test. While the car is idling funky, disconnect one plug wire at a time. You should see a difference in how the car runs. Yank #1 and note how the engine runs. Then reconnect and yank #2. Do this for all the wires. Should you remove a plug wire and it's like nothing happened, then that is likely the cylinder with the trouble.

Just a word of warning... be careful with this. Don't touch anything metal on the car while you're pulling the wires.

 

[knight007]

ok thanks like i said i have to wait awhile im at school right now.

 

[knight007]

fixed the problem it was both the spark plug wires and coil pack. i guess there was something wrong with the new plug wires? As for the coil pack i have no idea why all of a sudden that started working but im not complaining. Thanks for all the help and quick replies.